THE POPLITEAL SPACE

Dissection.-A vertical incision about eight inches in length should be made along the back part of the knee-joint, connected above and below by a transverse incision from the inner to the outer side of the limb. The flaps of integument included between these incisions should be reflected in the direction. 

Boundaries.-The popliteal space, or the ham, is a lozenge-shaped space, widest at the back part of the knee-joint, and deepest above the articular end of the femur. It is bounded externally, above the joint; by the Biceps, and, below the joint, by the Plantaris and external head of the Gastrocnemius. Internally, above the joint, by the Semimembranosus, Semitendinosus, Gracilis, and Sartorius; below the joint. by the inner head of the Gastrocnemius. 

Above, it is limited by the apposition of the inner and outer hamstring muscles; below, by the junction of the two heads of the Gastrocnemius. The floor is formed by the lower part of the posterior surface of the shaft of the femur, the posterior ligament of the knee-joint, the upper end of the tibia, and the fascia covering the Popliteus muscle, and the space is covered in by the fascia lata. Contents.-It contains the popliteal vessels and their branches, together with the termination of the external saphenous vein, the internal and external popliteal nerves and some of their branches, the lower extremity of the small sciatic nerve, the articular branch from the obturator nerve, a few small lymphatic glands, and a considerable quantity of loose adipose tissue. 

Position of Contained parts.-The internal popliteal nerve descends in the middle line of the space, lying superficial and crossing the artery from without inward. The external popliteal nerve descends on the outer side of the upper part of the space, lying close to the tendon of the Biceps muscle. More deeply at the bottom of the space are the popliteal vessels, the vein lying snperficial to the artery, to which it is closely united by dense areolar tissue; it is a thick¬walled vessel, and lies at first to the outer side of the artery, and then crosses it to. gain the inner side below; sometimes the vein is double, the artery lying between the two venre comites, which are usually connected by short transverse branches. More deeply, and, at its upper pa.rt, close to the surface of the bone, is the popliteal artery, and passing off from it at right angles are its articular branches. The articular branch from the obturator nerve descends upon the popliteal artery to supply the knee, and occasionally there is found deep in the space an articular filament from the great sciatic nerve.